Described herein is a display device for a motor vehicle. The display device is configured as a pointer instrument and has a pointer with a pointer needle in which a transparent lightguide emits light in a propagation direction toward a viewer.
Such pointer needles are typically used in display instruments in which a specific value is to be marked within a circular scale. In particular in the case of combination instruments, this involves, for example, a speed display (tachometer) or rotational speed display. In order to obtain a pointer needle of transparent lightguide, the pointer needle can be fabricated, for example, from PMMA or a polycarbonate (PC) and can have on an underside a hot stamping foil, by which light which is propagated in the lightguide is scattered in the emission direction.
Since the lightguide is transparent, in the dark, for example when traveling at night, generally only the scattering hot stamping foil is seen, which foil is perceived only as a diffuse bar, i.e. as a result of its scattering property. Therefore, a driver can undesirably take a long time to focus on the pointer needle when moving his gaze from the events on the road to the combination instrument.
German Patent Application No. 10 2008 011 062 A1 describes a multi-colored pointer for a measuring element which can generate at least two colors of light from a light source with a single color. The light is colored by using a film.
German Patent Application No. 36 28 540 A1 describes a pointer for a display instrument whose cross section is in the shape of an equilateral triangle, with the result that a colored layer can be seen on the underside from various directions of viewing the pointer, as a result of refraction and total reflection of the beam entry in the pointer.
Japan Patent Application No. 6-281751 A describes a pointer for a display instrument, into the transparent material of which a fluorescent substance is mixed. A curved groove scatters the fluorescent light into the surroundings.